INCREASED NUMBER OF EPSTEIN-BARR-VIRUS LATENTLY INFECTED B-CELLS IN T-CELL NON-HODGKINS-LYMPHOMA TISSUES

Epstein-Barr virus (EBV) is a causative agent of malignant lymphomas o ccurring in immunocompromised hosts. Similar lymphoid tumors can be in duced in mice with severe combined immunodeficiency (SCID mice) by tra nsplanting human B-cells with latently infected EBV. We have previousl y observed that when apparently EBV-negative lymphomas were engrafted into SCID mice, Il of 18 T-cell non-Hodgkin's lymphomas (NHLs) produce d EBV associated lymphomas, but only 2 of 30 engrafted with B-NHLs. Pr evious studies suggested that EBV-infected cell inducing lymphomas in SCID mice may preferentially exist in T-cell NHL tissues. To prove thi s assumption, in situ hybridization (ISH) using oligonucleotide probes for EBV-encoded small RNAs 1 (EBER1) was used in this study to demons trate EBV-bearing lymphocytes in NHL tissues. It was found that EBV-be aring cells existe in 9 of the 10 T-cell NHL surgical specimens. By co ntrast, in B cell NHLs, only 2 of 10 carried EBV-bearing cells. Furthe r semi-quantitative analysis demonstrated that apparently significantl y more EBV-bearing cells were present in T-cell NHL tissues than in B- cell NHLs. Moreover, these EBV-bearing cells in lymphoma tissues were shown to be of B-cell lineage, by the combinated analysis of immunosta ining with CD20 and ISH with EBER1. These results indicated the increa se of EBV-bearing B-cells in T-cell NHL tissues, suggesting the activa tion of B-cells with latently infected EBV by neoplastic T-cells.